The invention relates generally to camera positioning systems, and more particularly, to a method and apparatus for controlling the pan and/or tilt of a video camera in a videoconferencing environment.
Current videoconferencing systems, such as those manufactured by PictureTel Corporation, can include a moveable video camera which is controlled from a remote keypad. The remote keypad, in addition to providing both pan and tilt incremental controls, includes so-called presets which enable the user to store fixed positions of the camera for later recall. Accordingly, at later times during a videoconference, a single button commands the videoconferencing system to move the camera to a predetermined location.
Current technology, for high resolution systems, is relatively expensive. These systems can be open loop or closed loop, and can include varying control devices including optical striped encoders, Hall effect transducers, and other position sensing devices.
Capacitive sensors, which have been used in various specialized circuits, have been employed as rotary and linear position transducers in varying applications. Capacitive transducers, however, have not been used in instances where high resolution and low cost are the key requirements. Accordingly, they have not been used for controlling the pan and tilt of cameras in a videoconferencing environment.
It is therefore an object of the invention to provide a camera positioning system which is inexpensive, accurate, linear, and capable of high repeatability for absolute positioning. Other objects of the invention are a camera positioning system which is relatively immune from noise and grounding effects, and which has long life, high reliability, and good frequency response.